Setting up DNS

Steps to set up the DNS server for IBM Spectrum Fusion HCI appliance.

About this task

Note: The samples in this procedure are based on Red Hat® Enterprise Linux. If you are on Microsoft Windows, then use equivalent commands.

Procedure

Run the following command to suspend updates to all dynamic zones:
```
rndc freeze
```

Edit your forward lookup at /var/named folder:

Note: Forward look up returns IP address of a hostname.

Sample forward lookup file:

$TTL 1W
@       IN      SOA     ns1.isf.mycompany.com.      root (
                        2021052608      ; serial
                        3H              ; refresh (3 hours)
                        30M             ; retry (30 minutes)
                        2W              ; expiry (2 weeks)
                        1W )            ; minimum (1 week)
        
;
ns1                 IN  A       <dns-vip-ip>
api                 IN  A       10.44.100.143

; Ingress LB (apps)
*.apps          IN      A       10.44.100.144  //<wildcard-ingress-lb-ip>;
; Create entries for the master nodes
control-0       IN      A       10.44.100.145
control-1       IN      A       10.44.100.146
control-2       IN      A       10.44.100.147
;
; Create entries for the worker nodes
compute-0       IN      A       10.44.100.148
compute-1       IN      A       10.44.100.149
compute-2       IN      A       10.44.100.150
; AFM nodes
compute-13      IN      A       10.44.100.156
compute-14      IN      A       10.44.100.157
; GPU nodes
compute-15      IN      A       10.44.100.158
compute-16      IN      A       10.44.100.159
;
;EOF

Edit the reverse lookup file at /var/named/reverse.db folder.

Reverse look up returns hostname of an IP address.

Sample reverse lookup file:

$TTL 1W
@	IN	SOA	ns1.isf.mycompany.com.	root (
			2021052608	; serial
			3H		; refresh (3 hours)
			30M		; retry (30 minutes)
			2W		; expiry (2 weeks)
			1W )	; minimum (1 week)
	IN	NS	ns1.isf.mycompany.com.
;
143	IN	PTR	api.isf.mycompany.com.
151	IN	PTR	bootstrap.isf.mycompany.com.
;
; syntax is "last octet" and the host must have fqdn with trailing dot
145	IN	PTR	control-0.isf.mycompany.com.
146	IN	PTR	control-1.isf.mycompany.com.
147	IN	PTR	control-2.isf.mycompany.com.
;
148	IN	PTR	compute-0.isf.mycompany.com.
149	IN	PTR	compute-1.isf.mycompany.com.
150	IN	PTR	compute-2.isf.mycompany.com.
156	IN	PTR	compute-13.isf.mycompany.com.
157	IN	PTR	compute-14.isf.mycompany.com.
158	IN	PTR	compute-15.isf.mycompany.com.
159	IN	PTR	compute-16.isf.mycompany.com.
;
;EOF

In this example, the IP addresses 10.44.100.143-159 points to the corresponding fully qualified domain name.

Ensure that your named.conf file in the /etc folder contains details of your forward and reverse lookup files.

Sample named.conf file:

[root@provisioner named]# cat /etc/named.conf

options {
	listen-on port 53 { any; };
	listen-on-v6 port 53 { ::1; };
	directory 	"/var/named";
	dump-file 	"/var/named/data/cache_dump.db";
	statistics-file "/var/named/data/named_stats.txt";
	memstatistics-file "/var/named/data/named_mem_stats.txt";
	allow-query     { any; };
    .......
    .......
###### Add what's between these comments ###########
zone "isf.mycompany.com" IN {
	type	master;
	file	"zonefile.db";
};
zone "100.44.10.in-addr.arpa" IN {
	type	master;
	file	"reverse.db";
};
########################################################
include "/etc/named.rfc1912.zones";
include "/etc/named.root.key";

On the DNS server, run the following commands to open the firewall port for DNS:
```
firewall-cmd --zone=public --add-service=dns --permanent
firewall-cmd --reload
```